Question

Three liquids of different densities are mixed. Because they are not miscible (do not form a homogeneous solution with one another), they form discrete layers, one on top of the other. Sketch the result of mixing carbon tetrachloride \(\left(\mathrm{CCl}_{4}, d=\right.\) \(\left.1.58 \mathrm{g} / \mathrm{cm}^{3}\right),\) mercury \(\left(d=13.546 \mathrm{g} / \mathrm{cm}^{3}\right),\) and water \(\left(d=1.00 \mathrm{g} / \mathrm{cm}^{3}\right)\)

Short answer

Mercury at the bottom, carbon tetrachloride in the middle, water on top.

Step-by-step solution

Understand the Concept

In this exercise, we need to order three immiscible liquids based on their densities. The liquid with the highest density will form the bottom layer, and the liquid with the lowest density will form the top layer.

List the Densities

We have the following densities: 1. Mercury: \(13.546\, \text{g/cm}^3\)2. Carbon tetrachloride: \(1.58\, \text{g/cm}^3\)3. Water: \(1.00\, \text{g/cm}^3\)

Order the Liquids by Density

To create the stack of liquids from densest to least dense:- Mercury \((13.546\, \text{g/cm}^3)\) is the most dense, so it will be at the bottom.- Carbon tetrachloride \((1.58\, \text{g/cm}^3)\) is less dense than mercury but more dense than water, so it will form the middle layer.- Water \((1.00\, \text{g/cm}^3)\) is the least dense, so it will be at the top.

Sketch the Resulting Layers

Draw a vertical container and label it with three horizontal sections from bottom to top: - The bottom section is labeled "Mercury." - The middle section is labeled "Carbon Tetrachloride." - The top section is labeled "Water." This stack visually represents their arrangement by density.

Key concepts

Immiscible Liquids

Immiscible liquids are liquids that do not mix together to form a single homogeneous solution, meaning they cannot be blended into one continuous phase. When two or more immiscible liquids are combined, they separate into distinct layers. This separation happens due to differences in molecular structures, which lead to different interactions between the molecules of each liquid. Immiscible liquids repel each other rather than blend.

In everyday life and in laboratory conditions, many commonly used liquids display this property. A common example is oil and water. The oil molecules are non-polar, while water molecules are polar; this difference prevents them from mixing. Looking at carbon tetrachloride, mercury, and water, all these liquids exemplify immiscibility because their molecular structures vary significantly. As a result, they form separate layers when they are placed together in the same container.

Layered Arrangement

When immiscible liquids are poured into a container, they arrange themselves into layers. This arrangement is not random but determined by the densities of the liquids. Density is the mass per unit volume. The higher the density, the more mass there is in a specific volume.

• The liquid with the highest density will sink to the bottom of the container.
• Any liquid placed on top of this will have a lower density.
• Finally, the liquid with the lowest density will float on the topmost layer.

This layering creates a distinct, visible separation between each liquid.

In our exercise concerning carbon tetrachloride, mercury, and water, mercury has the highest density and forms the bottom layer. Carbon tetrachloride has a density between the other two liquids, so it forms a middle layer. Finally, water, with the lowest density, conforms to the topmost layer in the container.

Density Order

Understanding the density order of liquids is crucial in predicting how they will arrange themselves when combined. The key is to know the density of each liquid and then rank them from highest to lowest.

• Mercury: With a density of 13.546 g/cm³, it is the densest among the three liquids, and it occupies the bottom layer in the layered arrangement.
• Carbon Tetrachloride: This liquid has a density of 1.58 g/cm³. It is less dense than mercury but more than water, placing it in the middle layer.
• Water: With the lowest density of 1.00 g/cm³, water naturally forms the top layer when the three liquids are combined.

Grasping this concept allows students to not only solve exercises like this but also apply this knowledge to real-world scenarios, such as engineering and environmental science, where understanding liquid separation is crucial.